Hi, In message "[ruby-talk:20606] Re: String.subst[!] RCR" on 01/08/31, "Aristarkh A Zagorodnikov" <xm / w3d.ru> writes: |> Regular expression search is pretty fast for most of the cases |> (especially for fixed patterns). It uses BM search inside. |> As a result, str.sub(/foo/, 'bar') is often faster than your |> str.subst('foo','bar'). | |I'm sure it _is_ faster ... but I believe that's it because of subst is |written in ruby, while sub is in C. I meant RE substitute can be as fast as C implemeted subst. matz.